The purpose of the research is to determine the structure and function of Fc receptors foR IgE on lymphocytes and monocytes/macrophages. 1. Lymphocytes of patients with allergies to pollen will be analyzed for Fc eta receptors (Fc eta R) positive cells over a year period, before, during and after the grass pollen season. The lymphocytes will be cultured and the IgE produced in vitro measured employing unfractionated and Fc eta R depleted or enriched cells. 2. Monocytes will be purified from patients with allergic disease and studied for Fc eta R positive cells. It will be determined if phagocytosis of IgE coated target cells will cause release of slow reacting substance of anaphylaxis (SRS-A) from monocytes. 3. Rat alveolar and peritoneal macrophages will be analyzed for their ability to form rosettes with red cells coated with rat myeloma proteins of all classes and subclasses. Rat alveolar macrophages were shown to have Fc eta R and will be tested for release of SRS-A after interaction with aggregated IgE myeloma proteins. 4. The numbers of Fc eta R positive lymphocytes (both T and B cells) and macrophages will be determined in rats infected with Nippostronglyus brasiliensis parasites in various lymphoid organs. The number of receptors on these cells will be quantitated by measuring binding of radiolabeled IgE to isolated cells.